Collaborative Research: Overturning in the Subpolar North Atlantic-the Irminger and Iceland Basins

北大西洋热量、淡水和物质输送的可变性与若干社会相关因素有关，包括海平面变化、海洋和冰川融化以及深海人为碳储存。然而，目前对这种变化的驱动因素的了解有限，使调查亚极区的倾覆成为海洋研究的一个关键优先事项。这一实地考察计划明确解决了这一差距。此外，通过让更大的国际社会参与研究北大西洋，北大西洋次极地计划(OSNAP)正在通过促进国际合作、综合和资源共享以及通过培训子孙后代，在促进科学进步方面发挥关键作用。后者的关键是一个早期职业科学家网络，他们的专业成长将通过在OSNAP的初始阶段经过测试和改进的有针对性的活动继续得到促进。研究生和博士后将接受海洋作业以及观测数据处理和分析方面的培训。这一实地项目的总体目标是与北大西洋的其他测量一起，确定中水和深水形成与颠覆环流之间的联系--这种联系存在于气候模型中，但尚未观察到。该项目还将提供亚极地盆地深水扩散路径的第一个综合视图。从2014年开始，由美国牵头的国际项目-亚极地北大西洋翻转计划(OSNAP)与英国、荷兰、加拿大、德国和中国合作，提供了亚极地北大西洋全水柱、跨盆地热通量、质量通量和淡水通量的连续记录。OSNAP全观测系统头21个月的数据被用来生成亚极地盆地经向翻转、热量和淡水通量的初始时间序列。这些初步结果揭示了盆地中高度可变的倾覆、溢流水的内部通道、从几天到几个月的时间尺度上令人惊讶的能量边界流系统，以及冰岛盆地的强烈溢流羽流。OSNAP额外两年的观测将覆盖足够的时间框架，以与其他倾覆时间序列进行比较，并优化OSNAP测量系统--在请求进行更长期测量之前的所有必要任务。OSNAP(OSNAP East)的这一组成部分是格陵兰岛和苏格兰之间的东部阵列，与联合王国和荷兰协调。美国的贡献包括东格陵兰近岸和近海阵列、冰岛盆地阵列和所有OSNAP测量的整合。OSNAP East的次要目标是量化格陵兰东海岸和冰岛盆地内边界流的结构和输送，并确定它们的可变性和强迫机制。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Variability in the transport of heat, freshwater and mass in the North Atlantic has been linked to a number of societally relevant factors including sea level change, the melting of sea and glacial ice, and anthropogenic carbon storage in the deep ocean. However, the current understanding of the drivers of such changes is limited, making an investigation of overturning in the Sub-polar region a key ocean research priority. This field program explicitly addresses this gap. Furthermore, by engaging the larger international community studying the North Atlantic, Overturning in the Sub-polar North Atlantic Program (OSNAP) is playing a key role in catalyzing scientific progress by promoting international collaborations, synthesis, and the sharing of resources and by training future generations. Key to the latter is a network of early career scientists whose professional growth will continue to be facilitated through targeted activities that have been tested and improved during OSNAP's initial phase. Graduate students and post-docs will be trained in seagoing operations and in the processing and analysis of observational data.The overall goal of this field project, in conjunction with other measurements in the North Atlantic, is to establish determination of the linkage between intermediate and deep water formation and the overturning circulation--a connection that is present in climate models, but has yet to be observed. This project will also provide the first comprehensive view of spreading pathways for the deep waters in the Sub-polar basin. Starting in 2014, the US-led international project, Overturning in the Sub-polar North Atlantic Program (OSNAP), provides a continuous record of the full-water column, trans-basin fluxes of heat, mass and freshwater in the Sub-polar North Atlantic, in partnership with the UK, Netherlands, Canada, Germany and China. Data from the first 21 months of the full OSNAP observing system has been used to produce an initial time series of the meridional overturning, heat and freshwater fluxes for the Sub-polar basin. These preliminary results reveal a highly variable overturning in the basin, interior pathways for overflow waters, surprisingly energetic boundary current systems on timescales from days to months, and a strong overflow plume in the Iceland Basin. The additional two years of OSNAP observations will cover a time frame sufficient to make comparisons with other overturning time series and optimize the OSNAP measurement system--all necessary tasks prior to a request for longer term measurements. This component of OSNAP (OSNAP East) is for the eastern array between Greenland and Scotland in coordination with the UK and the Netherlands. The US contribution includes the East Greenland inshore and offshore arrays, the Iceland Basin array, and the integration of all OSNAP measurements. The sub-goal for OSNAP East is to quantify the structure and transport of the boundary currents off the east coast of Greenland and within the Iceland Basin, as well as determine their variability and forcing mechanisms.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.